Wind mills or wind motors on a vertical axis have been known for a long time, see GRACEY U.S. Pat. No. 1,352,952, and MOORE U.S. Pat. No. 1,915,689. Means moving vanes or paddles from a position substantially at right angles to the direction of the wind, to a position at which they are substantially parallel to the wind are well known; see MOORE, supra, and BAIR U.S. Pat. No. 4,303,835. The object in the various prior art references has been to provide continuous rotation of a shaft, see LINDHORN U.S. Pat. No. 6,619,921, even when the windmill itself is capable of being driven in a reverse direction, see OUELLET U.S. Pat. No. 5,126,584.
An excellent discussion of the prior art is set out in WO 2006/093790, published 8 Sep. 2006, incorporated by reference herein. “The windfin articulated wind-powered generator” of that applications uses as its driving force a lift force to produce a flapping motion. The present invention utilizes a drag force.
In the windmill of the present invention, the vanes, panels or paddles are designed to oscillate, going through on the order of 120° for a hinged type to 80° for a non-hinged type with flaps, and reversing, occupying a great deal less space than the conventional windmill. The windmill of this invention can be used in combination with the usual windmill of the lift type, which rotates on a horizontal axis, the sort of windmill now used extensively in windmill farms, for the generation of electricity. The latter windmills occupy a large amount of space. The panels or rotors of these windmills commonly describe a circle hundreds of feet in diameter, and the closest placement of adjacent windmills or turbines is recommended to be the length of at least five times the diameter of the wind turbine's rotor, so that the adjacent wind turbines in the array are often placed at a distance of a quarter of a mile to half a mile, so that the air stream has time to “recover”.